A coin recognizing device that recognizes a denomination or authentication of a coin checks various elements such as a diameter, a material, a design, and a thickness of the coin as a recognition target according to outputs from a magnetic sensor or an optical sensor. This check is performed by judging whether sensor outputs corresponding to the elements of a genuine coin are included in predetermined value ranges (hereinafter, a set of value ranges to be used for the judgment is referred to as “judgment frame”). A coin recognizing device that judges a denomination by using a judgment frame is disclosed in Patent Document 1, for example.
In the coin recognition by using the judgment frame, for example when all sensor output values are included in value ranges of a specific judgment frame, respectively, a coin is judged to be a genuine one of a denomination corresponding to the judgment frame. The judgment frame having a set of predetermined value ranges is used because even genuine coins have individual differences and also the sensors have individual differences. This is also because the respective sensor outputs vary between new coins that have recently been released and circulated coins that have already been circulated in the market. Therefore, when the judgment frame having a set of predetermined value ranges is used, erroneous rejection of a genuine coin can be prevented.
Collection of samples with large amounts of new coins and circulated coins is required to create the judgment frame for each denomination. For example, when recognition targets are Japanese coins, it is easy to acquire new coins and circulated coins in Japan. Therefore, there is no particular problem in creating judgment frames previously when a coin recognizing device is developed, or re-creating a new judgment frame when a new coin is released.
Patent Document 1: Japanese Patent Application Laid-open No. 2003-256902